This application claims the priority of Japanese Patent Application Nos. 10-89403 and 10-89404 filed on Mar. 17, 1998, Nos. 10-100097, 10-100098 and 10-100099 filed on Mar. 27, 1998 which are incorporated herein by reference.
1. Field of the Invention
The present invention relates to an air and water supply system for endoscopes, and more particularly, to an arrangement for flow control of air and water supply through air feed tubes and water feed tubes installed in endoscopes.
2. Description of the Prior Art
Endoscopes are conventionally provided with air feed tubes, water feed tubes, etc. through which air and water (liquid) are supplied to the tip of the endoscope to clean the viewing window (objective lens surfaces) at the tip or remove water-drops from it as well as to inflate a body cavity such as the stomach by the air sent into the body of the subject under observation. After use, endoscopes are cleaned and drained through the water feed tubes before storage.
FIG. 12 shows the configuration of a solenoid valve unit of a conventional endoscope. The water feed tube 2A and air feed tube 3A on the endoscope side are connected to the solenoid valve unit 1. The solenoid valve unit 1 comprises a water feed tube 2B, solenoid valve Va for controlling the opening and closing of the water feed tube 2B, air feed tube 3B, and solenoid valve Vb for controlling the opening and closing of the air feed tube 3B, wherein the water feed tube 2B is connected to a feed water tank 4 through a water feed tube 2C.
The solenoid valve unit 1 also contains an air and water supply pump 5, which is connected with the air feed tube 3B and a tube (air feed tube) for water supply 3C, which in turn is connected to the feed water tank 4 through a tube 3D. Furthermore the pump 5 is connected with an atmospheric escape pipe 6, which is equipped with a solenoid valve Vc. The control switch for air/water supply is installed, for example, on the operating section of the endoscope.
In the above configuration, when the air/water supply switch is not actuated, only the solenoid valve Vc remains open and the air sent from the pump 5 is released to the atmosphere through the atmospheric escape pipe 6. When the air/water supply switch is manipulated to supply water, the solenoid valve Va opens and the solenoid valves Vb and Vc close, allowing water to be supplied from the feed water tank 4 to the endoscope through the water feed tubes 2C, 2B, and 2A. When it is manipulated to supply air, the solenoid valve Vb opens and the solenoid valves Va and Vc close, allowing air to be supplied through the air feed tubes 3B and 3A.
Object of the Invention
The conventional air and water supply systems of endoscopes are not able to regulate flow rates (quantities of flow per unit time): they control only the on/off operation of air/water supply. They are not capable of providing optimum air/water (liquid) supply individually according to application. Although the system in FIG. 12 described above is capable of adjusting the flow rates of air and water by changing the supply air pressure (capacity) of the pump 5 itself, it has a problem that is impossible to control air supply and water supply separately because changing the supply pressure of the pump 5 for air flow control will also change the flow rate of water.
For example, shooting out water at a relatively high flow rate (in the state of a large quantity of water per unit time) produces good results when cleaning the viewing window, whereas for subsequent drying, it is better to inject air at a relatively low flow rate, which will eliminate tiny droplets on the objective lens surfaces. Also, when inflating a body cavity such as the stomach (pneumoperitoneum) to apply an endoscope, it is necessary to feed air, taking into consideration the condition of the patient. Therefore, it is desirable if air and water can be supplied at a proper flow rate to suit the specific purposes of individual procedures. Besides, changing the supply pressure of the pump 5 in FIG. 12 between air supply and water supply may obstruct procedures because of time lags.
Furthermore, the endoscope is drained through the water feed tube 2A and air feed tube 3B after use, but there is a disadvantage that the supply air pressure during draining depends on the capacity of the pump 5, making optimum draining impossible.
Summary of the Invention
The present invention has been made in view of the above problems. The object of the present invention is to provide an air and water supply system for endoscopes that makes it possible to control air flow and water flow rates independently and supply air and water according to each application.
On the other hand, endoscopes have a flush water inlet port and an injection water inlet port installed on a operating section or the like. That is, the flush water inlet port is connected to the water channel of the endoscope. And water supplied through the flush water inlet port under high pressure with a syringe or the like can remove a high level of contamination from the objective lens surfaces of the viewing window. Also, an injection channel is installed in the endoscope to inject water to the object of observation. It is connected with the injection water inlet port installed on the operating section or the like. A liquid such as physiological saline is supplied through the injection water inlet port with a syringe or the like to remove foreign matters which would obstruct observation or treatment by adhering to objects under observation.
However, high-speed water injection and lens surface flushing, which are carried out by the use of accessories such as a syringe from the flush water inlet port and injection water inlet port installed on the operating section, involve complicated operations. Besides, injection with a syringe requires skill and experience of the physician. Moreover, these operations require a fast and ample flow of water, which conventional pumps cannot provide.
Another object of the present invention is to provide an air and water supply system for endoscopes that will allow high-speed water injection and lens surface flushing to be performed with simple switch operations.
Furthermore, the air and water supply system for endoscopes shown in FIG. 12 employ flexible tubing made of polyvinyl chloride (PVC) or the like for the water feed pipe 2A and air feed pipe 3A which connect the solenoid valve unit 1 with, for example, the light source fitted to the endoscope. And it has a problem that these flexible pipes (2A and 3A) may deform during air or water supply, changing the flow rate and failing to dry the lens surface of the viewing window sufficiently.
That is, the diameters of the water feed pipes 2 and the like used in the endoscope increase with approach to the solenoid valve unit 1, for example, the channel diameter inside the endoscope being approximately 1 mm, the tube diameter in the cable being approximately 2 mm, and the diameters of the above-mentioned flexible connecting pipes (2A and 3A) being approximately 5 mm. The walls of the flexible pipes are subject to some internal pressure. Thus the flexible pipes (2A and 3A) expand under this pressure during air or water supply, changing the flow rate at the start or end of air or water supply.
Furthermore, after supplying water to the lens surfaces to clean the viewing window, the pressure produced by the expanded connecting pipe 6C returning to the original shape will cause a small amount of water to leak from the nozzle at the distal end of the endoscope, resulting in poor water removal.
Still another object of the present invention is to provide an air and water supply system for endoscopes that can prevent changes in the flow rate and correct insufficient water removal by suppressing the expansion of the connecting pipes between the endoscope and channel control unit.
To attain the above objects, the present invention is characterized by comprising a pump for supplying air and water to the distal end through the air and water channels, a plurality of open-close valves installed on the air channel, water channel, and atmospheric escape channel connected to the pump, and a flow control section for specifying the air flow rate in the air channel and water flow rate in the water channel independently by controlling these valves. The flow control section allows the physician to vary the air flow rate while keeping the water flow rate constant.
According to the above described present invention, it is possible to set the air flow rate and water flow rate to different values, for example, by dividing the atmospheric escape pipe into a plurality of branch pipes and installing a solenoid valve in each of the branch pipes. For example, closing both solenoid valves installed in two atmospheric escape pipes will provide a High flow rate and closing only one of them will provide a Low flow rate. It is possible to switch the air flow rate between the High and Low setting while keeping the water flow rate at the High setting. This will make it possible to control both air and water flow rates through simple installation of solenoid valves in atmospheric escape pipes, eliminating the need to install separate means of control for air and water supplies, thus simplifying the configuration of the system.
Another aspect of the present invention is characterized by comprising an air channel, a water channel, an air supply pump, a water supply pump for supplying water independently of the air supply pump, and a controlling section for controlling the air supply pump and the water supply pump separately to regulate the air flow rate and water flow rate.
This aspect of the present invention comprises a first connecting pipe connecting the air channel and the water channel as well as an open-close valve for controlling the opening and closing of the first connecting pipe, of which the controlling section can supply air to at least the air channel.
It also comprises a second connecting pipe for connecting the water supply pump to the water channel to supply air as well as an open-close valve for controlling the opening and closing of the second connecting pipe, wherein the controlling section can use two pumps to supply air to the water channel.
According to the present invention, since independent air and water supply pumps are employed, their capacities can be selected separately to suit the purposes of air supply and water supply. The flow control means can also be employed separately for air supply and water supply. This makes it possible to specify the air flow rate and water flow rate per unit time individually according to application. The use of the first connecting pipe and its open-close valve allows air to be supplied to the water feed tube by the air supply pump at the optimum pressure for draining. Since two pumps can be used together, for example, to supply air to the water feed tube, and the intensity of air supply can be selected according to the condition of draining in this case.
Moreover, this aspect of the present invention can comprise a third connecting pipe for connecting the air supply pump to the water channel to supply water as well as an oepn-close valve for controlling the opening and closing of the third connecting pipe, wherein the controlling section can use two pumps to supply water to the water channel.
It also comprises an injection channel, apart from the water channel, for injecting water to objects under observation, the injection channel being connected to the third connecting pipe to allow water to be supplied to the injection channel with two pumps.
According to this aspect of the present invention, if the air supply pump is connected, for example, to the water feed tube through the third connecting pipe and its open-close valve, both air and water supply pumps can be used to secure the force and quantity of water supply necessary to flush the lens surfaces. Advantageously, the air supply pump can also be connected through a connecting pipe and open-close valve to the injection channel installed apart from the water channel, to secure the force and quantity of water supply necessary for high-speed water injection by using both air and water supply pumps.
Still another aspect of the present invention comprises a channel for supplying air and water to the distal end, flow control means for controlling the flow rates of the air and water supply through this channel variably, a control switch for selecting the flow rate to be controlled by the flow control means and for performing the air or water supply, and a control section which controls the flow control means so as to supply air or water at a predetermined fixed flow rate for a specified time after the air supply or water supply operation is started by the control switch and then enable any flow rate specified by the control switch.
According to this aspect of the present invention, the flow control means incorporating, for example, multiple pairs of an atmospheric escape pipe and its open-close valve allows air supply and water supply to be controlled in two steps High and Lowxe2x80x94or any number of steps. Supposing that the High water flow setting and Low air flow setting are most desirable when cleaning the objective lens surfaces of the viewing window, the fixed flow rate of water supply is preset at High and that of air supply is preset at Low. Accordingly, when water supply is started, water is always supplied at the High flow rate for the first several seconds, and then it is supplied at the selected flow rate. On the other hand, when air supply is started, air is always supplied at the Low flow rate for the first several seconds, and then it is supplied at the selected flow rate. It is possible to limit the use of a fixed flow rate to either air supply or water supply.
Yet another aspect of the present invention is characterized in that the connecting pipe between the endoscope-side air or water feed tube and the corresponding tube on the side of the channel control unit is a flexible pipe, which is equal or superior to the air or water feed tubes inside the endoscope in terms of resistance to deformation caused by internal pressure.
This connecting pipe can be made by coating the outer surface of a soft tube with reinforcing material to protect the soft tube against deformation while maintaining its flexibility. Possible reinforcing materials include heat-shrinkable tubing, meshes, and adhesive coils. This aspect of the present invention can make the connecting pipe equal or superior to the air or water feed tubes inside the endoscope in terms of resistance to deformation, preventing expansion of the connecting pipe due to air or water pressure.